glibc/include/array_length.h

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/* The array_length and array_end macros.
Copyright (C) 2017-2019 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#ifndef _ARRAY_LENGTH_H
#define _ARRAY_LENGTH_H
/* array_length (VAR) is the number of elements in the array VAR. VAR
must evaluate to an array, not a pointer. */
#define array_length(var) \
__extension__ ({ \
_Static_assert (!__builtin_types_compatible_p \
(__typeof (var), __typeof (&(var)[0])), \
"argument must be an array"); \
sizeof (var) / sizeof ((var)[0]); \
})
/* array_end (VAR) is a pointer one past the end of the array VAR.
VAR must evaluate to an array, not a pointer. */
#define array_end(var) (&(var)[array_length (var)])
#endif /* _ARRAY_LENGTH_H */